WO2015044652A2

WO2015044652A2 - An apparatus and method of production for inflatable tubes

Info

Publication number: WO2015044652A2
Application number: PCT/GB2014/052872
Authority: WO
Inventors: Wilson ROLAND
Original assignee: Wilson Consultants And Management Limited
Priority date: 2013-09-24
Filing date: 2014-09-22
Publication date: 2015-04-02
Also published as: WO2015044652A3; GB201316972D0

Abstract

An inflatable tube, and its method of production, for use in mobile maritime apparatus comprising a continuous hollow structure, comprising a braid (10), coated with an elastomer (30) to provide a gastight barrier, and at least one separate internal bladder (12) made of impermeable material.

Description

An apparatus and a method of production for inflatable tubes

The present invention relates to an inflatable tube and its method of production, especially but not exclusively for use in mobile maritime apparatus such as inflatable boats, rigid hull inflatable boats and life rafts.

The use of an inflatable tube allows mobile maritime apparatus, such as in the opening paragraph, to maintain buoyancy. Such apparatus frequently consists of a gas filled tube which may either form a continuous ring or a U or V shaped construction which may also can be described as a parabolic arch. In previously proposed inflatable tubes for use in mobile maritime apparatus, the tubes consist of a single tube, most commonly made using an elastomer coated Nylon textile weave. These tubes are usually constructed in separate sections and normally comprise several flat panels of an elastomer coated textile weave such as Hypalon (Chlorosulphanated polyethylene synthetic rubber), or PVC or polyurethane coated textiles.

Constructing such a tube from a number of different panels that must be cut and glued together to form such a three-dimensional tube requires a labour intensive process and great care to be taken in making any joins which may also need reinforcing. Further, in time these tubes often develop leaks at the seams as the glue degrades with age and the environment. Any seam represents a potential weakpoint in such a structure regardless of the manner in which the materials are joined. Typical working pressures in these previously proposed inflatable tubes are around 20kPa.

A first aim of the present invention is to provide an inflatable tube that overcomes the disadvantages discussed above. A second aim of the present invention is to provide a simple and cost-effective method of producing such an inflatable tube in a desired shape for a mobile maritime apparatus.

Accordingly, a first aspect of the present invention is directed to an inflatable tube for use in mobile maritime apparatus comprising a continuous hollow structure, comprising a braid, coated with an elastomer to provide a gastight barrier, and at least one separate internal bladder made of impermeable material. The elastomer can also provide increased strength and resistance to ultraviolet light, chemicals and mechanical abrasion. The internal bladder not only provides subdivision of the structure to aid buoyancy in the event of damage, but it may also serve, in certain embodiments of the present invention, to form a male mould or mandrel over which the braid is drawn to form its shape in three dimensions during construction, after which the ends of the braided tube are sealed and the whole structure is coated in an elastomer.

This provides amongst others the following advantages. The number of separate parts are reduced resulting in savings in the manufacturing process and allowing simplified mass production. The potential for structural failure is reduced due to the decrease in the number of joins. Use of braid increases the quality and strength of the inflatable tube, with the potential for higher working pressures. Using a braid also makes it easier for the take up of coatings, such as polyurethane or polyurea, and also to attach other apparatus to the inflatable tube. A further advantage is that by coating the entire structure with an elastomer such as polyurethane or polyurea any joints/seams are reinforced by polyurethane or polyurea which has a high tear resistance strength and high gas impermeability.

In a preferred embodiment the angle of the braid is varied to alter material properties of the inflatable tube. This provides the advantage that the tube can have different characteristics with regard to for instance its curvature. By way of an example, a single piece of braided textile can be used to formulate a complex curve without the need for seams.

A double skin is created with an outer braid covering the inflatable bladder. The inflatable bladder is inflated to a lower pressure than the volume between the bladder and the outer braided layer meaning that upon puncturing of the braided layer the internal bladder or bladders will expand as the external air pressure acting on them decreases and fill the inside of the tube thus maintaining shape and performance of the vessel.

Preferably the braid is a braided fabric. This provides the advantage of ease of manufacture.

Preferably the braid consists of a para-aramid fibre. This provides the advantage that the resultant inflatable tube can contain up to and around 2000kPa of pressure.

Advantageously, the inflatable tube is coated externally and/or internally with an elastomer coating to maintain designed shape, provide an impermeable layer and to give the structure increased strength, resistance to ultraviolet light, chemicals and mechanical abrasion.

A second aspect of the present invention is to provide a method of producing an inflatable tube, especially but not exclusively for use in mobile maritime apparatus comprising a continuous hollow structure, which is comprised of a braid, and a separate internal bladder made of impermeable material, said inflatable tube’s method of production comprising the steps of;

Providing an inflatable male mould made of an impermeable material;

Inflating said mould;

Applying a coating of an elastomer to the entire mould surface;

applying an adhesive layer to the surface of the elastomer;

Applying a continuous hollow structure, which is comprised of a braid or a textile, over the mould;

activating the adhesive layer as required;

deflating and removing the mould from the inside of the hollow structure;

turning the new structure inside out; and

inserting a bladder(s) into the hollow structure.

An alternative method of production of the said inflatable tube comprises the steps of:

providing a tubular bladder made of an impermeable material;

inflating such a tubular bladder;

applying a continuous hollow structure, which is comprised of a braid, over the tubular bladder; and

coating the structure with an impermeable layer.

Advantageously the adhesive layer is a latent heat adhesive that can be activated by applying a vacuum to the structure followed by heating. Alternatively, the adhesive layer is a textile that comprises yarns made of a thermoplastic resin in combination with other yarns, that can also be activated by heating.

Advantageously, the bladder is equipped with a rubber ring that will aid the securing of the braid and will also form a bow.

Preferably the bladder ends are conical. This provides the advantage that the braid can be secured more effectively.

Preferably moulded conical tube ends are fitted over onto the conical bladder ends and secured to the braid. Inflation valves are fitted through these conical tube ends. This provides the advantage that inflation valves can be fitted through the conical tube ends to allow for the air space between the braid and bladder and/or the bladders to be inflated. This eliminates a potential weakness common in existing tubes by inserting the inflation valve through the elastomer coated textile.

Examples of inflatable tubes made in accordance with the present invention will now be described in relation to the accompanying drawings, in which:

Figure 1 shows a plan view of an inflatable tube with a ‘scow’ bow;

Figure 2 shows a plan view of an inflatable tube with a pointed bow;

Figure 3 shows a cross-sectional view of a pointed bow ring;

Figure 4 shows a plan view of an inflatable tube ends.

Figure 5 shows a further plan view of an inflatable tube

Figure 6 shows a cross-sectional cut-away view of an inflatable tube

Figure 1 shows a braid (10), produced on a large scale braiding machine which has a diameter approximately equivalent to that of the desired finished inflatable tube, being passed over an internal bladder (12) or a mould (X). The inflatable bladder (12)or a mould (X)has an approximate U shape which mirrors the desired shape of the flotation tanks of a rigid inflatable boat (RIB) and has a scow bow.

Figure 2 shows the braid (10) being passed over an internal bladder (12) or a mould (X) that has a pointed bow (14). The braid (10) is secured into the edge of an annular bow ring (18) on each side. The bow ring (18) is made from a tough rubber material which on completion will form the bow of the boat. The braid (10) is cut at an angle on each side of the bow ring (18) to assist smooth joining of the inflatable tube to the bow ring (18). The bow ring (18) is equipped with a valve (20) for inflation of the internal bladder or bladders (12). This avoids any break being necessary in the braid (10) to inflate the bladder or bladders (12).

Figure 3 shows a cross-sectional view of the bow ring (14). The bow ring (14 has an annular slot (18) for insertion and securing, by an adhesive, of the braid (10) on each side. The bow ring (14) also forms a strengthened abrasion resistant area at the bow of the RIB where mooring lines may pass over the tube and where contact with other vessels is likely.

Figure 4 shows a bladder end (22) which is cone shaped. Here the braid (10) is stretched over the ends of the bladder and tapered in a conical fashion around a conical cone end (26), utilising the properties of the braid to do so. Around the circumference of the conical tube end (26) there is an annular slot allowing the braid (10) to be inserted and secured by adhesive. The conical tube ends (26) contain a hole (24) through which an inflation valve can be fitted allowing the bladder (12) to be connected on the inside of the conical tube end (22) and for one or more valves to be connected from the inside to the outside via a conical tube end (26). If more than one side tube bladder is fitted then there will be a corresponding number of holes for inflation valves. An additional valve is inserted in the fitting (24) to allow the air space between braid and bladder to be inflated.

Figure 5 shows the braid (10) after it has been passed over an inflated mould (13). The inflated mould (13) can be deflated and removed through a valve hole (28) in the braid (10).

Figure 6 shows the material make up of an inflatable tube, as made in one method of its construction. The outermost external surface is that of the elastomer coating (30). There is than an adhesive layer (32) at the interface between the braid (10) and the elastomer coating (30). An internal bladder(s) (12) is on the inside and valves (34) are positioned for inflation of the outer braid containing layer and inflation of the internal bladder (12). Relief valves are also added to the structure to prevent over inflation.

In one method of construction of an inflatable tube the mould (13) is first inflated and then coated with an elastomer. This elastomer coating (30) is then covered with an adhesive, preferably a latent heat adhesive. The braid (10) is then passed over the mould (13) in sections. The section of the braid (10) fitting around the valve (34) is then cut to introduce an aperture to allow access to the valve (34) . The whole construction is then placed into a vacuum bag and heated so as to activate the adhesive layer (32) between the elastomer (30) and the braid (10). Heat can be applied by way of electric blankets or any such heat source that can be applied uniformly around the structure. The temperature is raised until it is above the activation temperature of the adhesive (typically around 70

C). As an alternative to the use of a latent heat adhesive, a braid may be used that incorporates a thermoplastic yarn. Adhesion is also achieved by use of a vacuum and the application of heat.

After activation of the adhesive is complete the heat source and vacuum bag are removed. The mould (13) is deflated via the valve (34), and the deflated mould (13) is then removed through the aperture (28) in the braid (10). The braid (10) is then turned inside out by running it through the aperture (28). The braid now has its elastomer coating (30) on its outermost side. The elastomer coating (30) provides a gastight barrier to air, water, chemicals and UV light. This coating (30) also aids to lock in the shape of the tube and provide additional strength and resistance to mechanical abrasion.

A bladder(s) (12) is then inserted through the aperture (28) into the hollow structure of the braid (10). Further apertures can be cut into the braid (10) to allow for valves to be introduced. The valves aid inflation of the outer braid containing layer and inflation of the internal bladder (12). Relief valves can also be added to the structure to prevent over inflation. Upon use, the user can first inflate the bladders (12) to a given pressure, then inflate the airspace between braid (10) and bladder (12) to a higher pressure. This creates a double skin design with the advantage that upon puncturing the braided layer (10) the internal bladders (12) will expand as the external air pressure on them decreases and fills the inside of the braided tube (10) to maintain shape and performance of the vessel.

Any apertures are then sealed using patches made of braid (10) and elastomer coating (30), then adhering. Alternatively, a simple patch made from other impermeable materials may be glued over the aperture.

Additional fittings such as handles, lifelines and wear patches can also be added to the inflatable tube.

During another method of construction of the inflatable tube, the bladders (12) are inflated then covered with briad (10). A bow ring (18) is placed at the bow/front of the bladders and moulded rubber cones (26) are placed at the stern ends of the bladders (12). The braid (10) is secured within the annular slots within the bow ring (18) or moulded rubber cones (26) with an adhesive, or similar.

The inflatable tubes are sprayed with a polyurethane coating to add strength and form a barrier to air, water, chemicals and UV light. This coating also locks in the shape of the tube so that it is no longer reliant upon the internal bladder.

When the sprayed on polyurethane coating has cured, additional fittings such as handles, lifelines and wear patches can be added to the tube.

Upon use, the user can first inflate the bladders (12) to a given pressure, then inflate the airspace between braid (10) and bladder (12) to a higher pressure. This creates a double skin design with the advantage that upon puncturing the braided layer (10) the internal bladders (12) will expand as the external air pressure on them decreases and fills the inside of the braided tube (10) to maintain shape and performance of the vessel.

As a variation to the design of the rubber cones (26) at the bladder ends (22), an inspection hatch can be fitted, with the bladder and valves secured into said hatch via screw threads. When the tubes are deflated the hatch can be removed allowing access to the inside of the inflatable tube for repairs and for the removal and replacement of bladders.

Claims

An inflatable tube for use in mobile maritime apparatus comprising a continuous hollow structure, comprising a braid, coated with an elastomer to provide a gastight barrier, and at least one separate internal bladder made of impermeable material.
An inflatable tube according to claim 1 in which the braid is a textile.
An inflatable tube according to claim 1 in which the braid is a fabric.
An inflatable tube according to claim 1 in which the braid consists of a para-aramid fibre.
An inflatable tube according to any preceding claim in which the elastomer is polyurethane or polyurea.
An inflatable tube according to any preceding claim in which the elastomer coating is applied externally and/or internally.
An inflatable tube according to any preceding claim, and further comprising an adhesive layer at the interface between the braid and the elastomer coating.
An inflatable tube according to claim 7, in which the adhesive layer is a latent heat adhesive.
An inflatable tube according to any preceding claim, and further comprising a braid that comprises yarns made of a thermoplastic resin as an adhesive source.
An inflatable tube according to any preceding claim, and further comprising a braid that comprises an adhesive layer or yarn that can be activated by heating.
An inflatable tube substantially as described herein, with reference to the accompanying drawings.
A method of producing an inflatable tube, especially but not exclusively for use in mobile maritime apparatus comprising a continuous hollow structure, which is comprised of a braid, and a separate internal bladder made of impermeable material, said inflatable tube’s method of production comprising the steps of;

Providing an inflatable male mould made of an impermeable material;

Inflating said mould;

Applying a coating of an elastomer to the entire mould surface;

Applying an adhesive layer to the surface of the elastomer;

Applying a continuous hollow structure, which is comprised of a braid or a textile, over the mould;

Activating the adhesive layer as required;

Deflating and removing the mould from the inside of the hollow structure;

Turning the new structure inside out; and

Inserting a bladder(s) into the hollow structure.
A method of producing an inflatable tube, in which the male mould has an approximate U shape which mirrors the desired shape of the flotation tanks of a rigid inflatable boat (RIB) and has a scow bow.
A method of producing an inflatable tube, especially but not exclusively for use in mobile maritime apparatus comprising a continuous hollow structure, which is comprised of a braid, and a separate internal bladder made of impermeable material, said inflatable tube’s method of production comprising the steps:

Providing a tubular bladder made of an impermeable material;

Inflating such a tubular bladder;

Applying a continuous hollow structure, which is comprised of a braid, over the tubular bladder; and

Coating the structure with an impermeable layer.
A method of producing an inflatable tube according to claim 14, in which the bladder is equipped with a rubber ring that will aid the securing of the braid and will also form a bow.
A method of producing an inflatable tube according to claim 14 or claim 15, in which the bladder has an approximate U shape which mirrors the desired shape of the flotation tanks of a rigid inflatable boat (RIB) and has a scow bow.
A method of producing an inflatable tube according to any of claims 14 to 16, in which the bladder ends are conical to enable the braid to be secured more effectively.
A method of producing an inflatable tube according to claim 17, in which moulded conical tube ends are fitted over the conical bladder ends and secured to the braid.
A method of producing an inflatable tube according to claim 17 or 18, in which inflation valves are fitted through the conical tube ends. This eliminates a potential weakness common in existing tubes by inserting the inflation valve through the elastomer coated textile.